Back-rest having two oval shaped shells each concave to vertical and convex to horizontal

ABSTRACT

A backrest for stools, seats, chairs, and the like, characterized by two backrest shells (1) that are arranged at the sides and are configured in the manner of the contact surfaces of equestrian saddles, these being configured so as to be concave with reference to an axis that is essentially perpendicular to the seating surface (20), and so as to be convex with reference to a horizontal axis above the seating surface (20).

BACKGROUND OF THE INVENTION

The present invention relates to a backrest for a chair, seat, stool, orthe like.

Backrests for chairs, automobile seats, and the like that incorporateside pieces that fit beneath the armpits and thus support the spine areknown (DE-PS 12 82 264). Such seats can also be configured as foldingseats when they are used in automobiles (DE-OS 20 49 666), such seatsautomatically deploying when sat upon. None of these backrests have beenaccepted because they were to costly to produce and they did not off therequired degree of comfort.

It is the task of the present invention to configure a backrest so thatthe spine of a seat person is effectively relieved of stress, thistaking place both in the case of longer periods when seated in changingpositions and also when widely differing physical characteristics of theindividuals using the seats are involved.

SUMMARY OF THE INVENTION

The invention provides a backrest for stools, seats, chairs, and thelike, characterized by two backrest shells that are laterally spaced andare configured in the manner of the contact surfaces of equestriansaddles, so as to be horizontally concave and vertically convex towardsthe front, a spring element being secured between a support rail andeach backrest shell so as to provide a positive connection.

The underlying concept of the present invention lies in the specialconfiguration of the seat shells. A configuration of this kind meansthat despite varying physical characteristics, persons using the seatare always supported, which is of particular importance in the case ofautomobile seating, since lateral forces must also be accommodated bythe backrest, and this can be done in an anatomically effective mannerby the backrest according to the present invention, so that the pelvicand lumbar regions are relieved of stress.

The present invention proposes a backrest that, in addition to beingsimple to produce, also offers a high level of comfort and adequatesupport for the spine. In addition, this backrest adapts to the physicaldimensions of various users.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basisof the drawings appended hereto. These show the following:

FIG. 1 A side view of a backrest according to the present invention.

FIG. 2 A rear view of the backrest shown in FIG. 1.

FIG. 3 A cross section on the line A-B in FIG. 2.

FIG. 4 A perspective rear view of a part of a modified embodiment of abackrest according to the present invention.

DETAILED DESCRIPTION

The backrest consists of two backrest shells 1 (FIGS. 1 to 3), that areheld by a spring rod 2 through carrier rails 3 and 4. These shells areshaped so as to be concave to the body around the vertical axis (FIG.3), whereas they are convex about a transverse horizontal axis (FIG. 1).In other words, the shells are horizontally concave and verticallyconvex towards the front side. Each spring rod 2 is connected at or nearits midpoint with a retaining or transverse rod 3 so as to form ashape-locking fit. The transverse rail 3 can, optionally, be connectedto a vertical carrier rail 4 of a chair so as to be adjustable inheight.

In order to provide for greater comfort, there can be a pad 6 fitted infront of or behind the backrest shells 1; if this pad is fitted behindthe shells 1, it is preferred that it be attached elastically to thespring rods 2.

When the user leans back against the backrest, there backrest shellsfold under the ribcage and the armpits of the person who is seated,thereby supporting the spine. The backrest shells can, however, rotateabout the horizontal axis, if the user wishes to lean right back. Inthis case, the spring rods 2 are stressed so as to flex. A lateralelastic flexing of the backrest shells 1 is also possible, when anelastic lengthening of the spring rods 2 that is coupled with flexing atthe point of attachment also takes place.

A similar mobility can be achieved if one connects the backrest shellsto the transverse rod 3 only with rubber cylinders 5 (FIG. 4).

Accordingly, there have been disclosed improved backrests. It isunderstood that the above-described embodiments are merely illustrativeof the application of the principles of this invention. Numerous otherembodiments maybe devised by those skilled in the art without departingfrom the spirit and scope of this invention, as defined by the appendedclaims.

We claim:
 1. Backrest characterized by two backrest shells (1), theshells being laterally spaced and configured so as to be substantiallyoval-shaped and elongated in the vertical direction when viewed inelevation as well as being concave with respect to an axis vertical to aseat surface (20) and convex with respect to a transverse horizontalaxis arranged above the seat surface (20) a transverse rail (3), andmeans for resiliently connecting each backrest shells to each berotatable about so as to enable said backrest shells to each berotatable about three spatial axes.
 2. Backrest as defined in claim 1further characterized in that for each of the backrest shells, saidresilient connecting means includes a spring element (5) extending fromsaid transverse rail to a central portion of the backrest shell. 3.Backrest as defined in claim 2 further characterized in that said springelement comprises a cylinder formed of rubberlike material.
 4. Backrestas defined in claim 1 further characterized in that for each of thebackrest shells, said resilient connecting means includes a spring rod(2) having its ends connected to the upper and lower ends of thebackrest shell and an intermediate portion connected to the transverserail.
 5. Backrest as defined in claim 1 further characterized by asubstantially vertically oriented pad (6) positioned proximate thebackrest shells.